There are a couple calls that look unnecessary noted below.
Other than that:

Reviewed-by: Josh Durgin <[email protected]>

On 04/29/2013 11:00 AM, Alex Elder wrote:
Define a new function rbd_dev_unprobe() which undoes state changes
that occur from calling rbd_dev_v1_probe() or rbd_dev_v2_probe().
Note that this is a superset of rbd_header_free(), which is now
getting removed (it seems to have been used improperly anyway).

Flesh out rbd_dev_image_release() so it undoes exactly what
rbd_dev_image_probe() does.

This means that:
     - rbd_dev_device_release() gets called when the last device
       reference gets dropped;
     - that undoes everything done by the rbd_dev_device_setup() call
       at the end of rbd_dev_image_probe() (and nothing more), ending
       by calling rbd_dev_image_release(); and
     - rbd_dev_image_release() undoes everything else done by
       rbd_dev_image_probe() (and this includes a call to
       rbd_dev_unprobe().

This means the image and device portions of an rbd device are fairly
cleanly separated now, so error paths should be a little easier to
verify than they used to be.

Signed-off-by: Alex Elder <[email protected]>
---
  drivers/block/rbd.c |   78
+++++++++++++++++++++++++--------------------------
  1 file changed, 39 insertions(+), 39 deletions(-)

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index feaa2e9..595d7b3 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -900,18 +900,6 @@ static void rbd_dev_clear_mapping(struct rbd_device
*rbd_dev)
        rbd_dev->mapping.read_only = true;
  }

-static void rbd_header_free(struct rbd_image_header *header)
-{
-       kfree(header->object_prefix);
-       header->object_prefix = NULL;
-       kfree(header->snap_sizes);
-       header->snap_sizes = NULL;
-       kfree(header->snap_names);
-       header->snap_names = NULL;
-       rbd_snap_context_put(header->snapc);
-       header->snapc = NULL;
-}
-
  static const char *rbd_segment_name(struct rbd_device *rbd_dev, u64 offset)
  {
        char *name;
@@ -4588,6 +4576,27 @@ out:
        return ret;
  }

+/* Undo whatever state changes are made by v1 or v2 image probe */
+
+static void rbd_dev_unprobe(struct rbd_device *rbd_dev)
+{
+       struct rbd_image_header *header;
+
+       rbd_dev_remove_parent(rbd_dev);
+       rbd_spec_put(rbd_dev->parent_spec);
+       rbd_dev->parent_spec = NULL;
+       rbd_dev->parent_overlap = 0;
+
+       /* Free dynamic fields from the header, then zero it out */
+
+       header = &rbd_dev->header;
+       rbd_snap_context_put(header->snapc);
+       kfree(header->snap_sizes);
+       kfree(header->snap_names);
+       kfree(header->object_prefix);
+       memset(header, 0, sizeof (*header));
+}
+
  static int rbd_dev_v1_probe(struct rbd_device *rbd_dev)
  {
        int ret;
@@ -4809,10 +4818,20 @@ static int rbd_dev_header_name(struct rbd_device
*rbd_dev)

  static void rbd_dev_image_release(struct rbd_device *rbd_dev)
  {
-       rbd_header_free(&rbd_dev->header);
-       rbd_assert(rbd_dev->rbd_client != NULL);
-       rbd_spec_put(rbd_dev->parent_spec);
+       int ret;
+
+       rbd_dev_remove_parent(rbd_dev);

This was just moved to rbd_dev_unprobe(), which is called in two lines.
It seems like this call should go away, since rbd_dev_unprobe() is also
used in an error path.

+       rbd_remove_all_snaps(rbd_dev);
+       rbd_dev_unprobe(rbd_dev);
+       ret = rbd_dev_header_watch_sync(rbd_dev, 0);
+       if (ret)
+               rbd_warn(rbd_dev, "failed to cancel watch event (%d)\n", ret);
        kfree(rbd_dev->header_name);
+       rbd_dev->header_name = NULL;
+       rbd_dev->image_format = 0;
+       kfree(rbd_dev->spec->image_id);
+       rbd_dev->spec->image_id = NULL;
+
        rbd_dev_destroy(rbd_dev);
  }

@@ -4854,7 +4873,7 @@ static int rbd_dev_image_probe(struct rbd_device
*rbd_dev)

        ret = rbd_dev_snaps_update(rbd_dev);
        if (ret)
-               goto err_out_watch;
+               goto err_out_probe;

        ret = rbd_dev_spec_update(rbd_dev);
        if (ret)
@@ -4865,15 +4884,14 @@ static int rbd_dev_image_probe(struct rbd_device
*rbd_dev)
                goto err_out_snaps;

        ret = rbd_dev_device_setup(rbd_dev);
-       if (ret)
-               goto err_out_parent;
+       if (!ret)
+               return 0;

-       return ret;
-err_out_parent:
        rbd_dev_remove_parent(rbd_dev);

This call is removed in the next patch, but should probably be removed
here, since rbd_dev_unprobe() calls it now.

-       rbd_header_free(&rbd_dev->header);
  err_out_snaps:
        rbd_remove_all_snaps(rbd_dev);
+err_out_probe:
+       rbd_dev_unprobe(rbd_dev);
  err_out_watch:
        tmp = rbd_dev_header_watch_sync(rbd_dev, 0);
        if (tmp)
@@ -5005,7 +5023,6 @@ static void rbd_dev_remove_parent(struct
rbd_device *rbd_dev)
                struct rbd_device *first = rbd_dev;
                struct rbd_device *second = first->parent;
                struct rbd_device *third;
-               int ret;

                /*
                 * Follow to the parent with no grandparent and
@@ -5016,11 +5033,6 @@ static void rbd_dev_remove_parent(struct
rbd_device *rbd_dev)
                        second = third;
                }
                rbd_assert(second);
-               ret = rbd_dev_header_watch_sync(rbd_dev, 0);
-               if (ret)
-                       rbd_warn(rbd_dev,
-                               "failed to cancel watch event (%d)\n", ret);
-               rbd_remove_all_snaps(second);
                rbd_bus_del_dev(second);
                first->parent = NULL;
                first->parent_overlap = 0;
@@ -5065,19 +5077,7 @@ static ssize_t rbd_remove(struct bus_type *bus,
        spin_unlock_irq(&rbd_dev->lock);
        if (ret < 0)
                goto done;
-
-       ret = rbd_dev_header_watch_sync(rbd_dev, 0);
-       if (ret) {
-               rbd_warn(rbd_dev, "failed to cancel watch event (%d)\n", ret);
-               clear_bit(RBD_DEV_FLAG_REMOVING, &rbd_dev->flags);
-               smp_mb();
-               return ret;
-       }
        ret = count;
-
-       rbd_dev_remove_parent(rbd_dev);
-
-       rbd_remove_all_snaps(rbd_dev);
        rbd_bus_del_dev(rbd_dev);
        module_put(THIS_MODULE);
  done:


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